Subsea pump systems normally have a motor that drives a pump. The system, motor and pump are normally hydraulic or electro hydraulic. In an open-loop hydraulic drive system or circuit a hydraulic motor is used to drive the hydraulic pump that is used to move another fluid, often called a media fluid, which can be seawater, between a first and a second location. Existing systems such as these are used to close blowout preventer (BOP) rams.
Subsea pump systems having two pumps have been used in the past for closing BOP rams. Typically one of the pumps is a high flow pump and the other pump is a high pressure pump.